I had a YS .63 on my Ultra Stick 40. I really like this engine, and considered getting another one for the Mustang. I ended up picking up a YS .91AC in the swapshop, but have decided against using this one on the Mustang as it weighs quite a bit more than the Saito. Out field is on the small (and rough!) side, so heavy planes tend not to last long.

The YS .91 will be going onto my UCD3D.